use thread_local for ntoa buf

@@ -1133,11 +1133,11 @@
 BUILD.s=        $(AS) $(ASFLAGS) $< -o $@
 
 # Override this top level flag so the compiler builds in its native
 # C99 mode.  This has been enabled to support the complex arithmetic
 # added to libc.
-CSTD=   $(CSTD_GNU99)
+CSTD=   $(CSTD_GNU11)
 
 # libc method of building an archive
 # The "$(GREP) -v ' L '" part is necessary only until
 # lorder is fixed to ignore thread-local variables.
 BUILD.AR= $(RM) $@ ; \